Whiteley Style Quadrant - Trigonometer Made by Danner Circa 1840s

There are very few American designed and patented surveying instruments, The major ones - Hanks Bow Compass, Burt's Solar Compass, and Young's Improved (Railroad) Compass (which would lead to the design of the first American Transit). Another American, Francis Whiteley of Standardsvill Virginia, designed and patented a very interesting surveying instrument in 1836. This instruments was in the nature of a quadrant, but contained a trough compass, a Goldsmith Chandlee L-T Table, and a few other interesting features. As Whiteley was not an instrument maker, it is generally believed that George Graves (who apprenticed with Goldsmith Chandlee) made the first instrument for Whiteley (and placed the L-T Table on it), while Jacob Danner made the subsequent Whiteley patent instruments,

In 1842, another Virginia resident (Benjamin Benton) was granted a patent for an improved version of Whiteley's Quadrant - Benton's patent added a sine grid to Whiteley instrument, which basically turned the instrument into a Trigonometer. It is believed that either Jacob Danner or his son, Jacob S. Danner made the instruments based on Benton's patent.

Finally, George Whitescarver, who also resided in Virginia, evolved the Tirgonometer even more by adding a vernier to it. Apparently Whitescarver received a patent on his instrument from the Confederate government, but I have not seen any proof of this patent. It is believed that Whitescarver made all of the instruments based on this evolved design.

These are fascinating and highly collectible instruments. They could measure either horizontal or vertical angles, and after the Benton improvement in 1842 the instrument could allow for slope reduction and trigonomic calculations.